In a stringed musical instrument, such as a guitar, the strings, placed under tension, extend unsupported between a first critical point usually formed by the nut positioned where the neck joins the head and a second critical point usually formed by a clearly defined point on the bridge connected to the body. The strings are secured or fixed at one end on the body of the instrument to what is traditionally known as the tailpiece, strung over the bridge and extended past the first critical point on the nut. In conventional instruments the strings are secured beyond the nut to the tuning pegs where an untensioned string is tensioned and adjusted to a tuned condition or proper playing pitch for play; sometimes a nut arrangement for securing the strings is provided for a headless or tuning peg-less design. The tension of an individual guitar string is approximately 10 lbs at typical tuned conditions; anchoring or securely attaching the string holds the string to the instrument under normal conditions that often comprise an excess of 10 lbs of tension per string under other certain circumstances.
The second critical point can be created as a part of a combined bridge and tailpiece structure. Traditionally, the size of the bridge element is quite small so as to create a clearly defined single point of contact between the string and the bridge element. It is between these two points that the playable string length is typically determined, sometimes referred to as the scale length. Adjusting the relative distance between the first and second critical points is called harmonic tuning. Some bridges structures are individually adjustable, that is for each string, relative to the nut for achieving a more precise harmonic tuning. Usually this adjustment of the second critical point for harmonic tuning is carried out first and then the strings of the instrument are tuned to playing pitch. Often referred to as the “setup”, it is not uncommon that further adjustment of the harmonic tuning is necessary for a variety of reasons, for example, including changing the brand of a string where the alloy of the strings is varied or when the gauge of strings the player chooses changes. The term “intonation module” refers to a device, one for each string of a stringed musical instrument, comprising a bridge element forming a second critical point adjustably positioned on the body relative to the nut or the first critical point for harmonic tuning, and one additional element, such as, for example, a tailpiece element for fixedly securing the associated string to the body, or an alternate tailpiece, or a string tuning element to pitch tune and/or adjust the tension of the associated string such as a macro-tuner or a fine-tune or parts thereof. Intonation modules can include aspects such as a base, a front end or leading edge closer to the nut, a rear edge or trailing edge further the nut, formed with recesses, restricted portions, hollow portions, etc., adjustably secured to a base plate that in some cases may comprise a tremolo in general or fulcrum tremolo in particular.
Often the typical construction of the strings, particularly for guitar and bass, includes a plain end and, on the other end, a “ball end” which being a washer-like addition is wrapped by the string itself into a larger form to help in “fixing” or securing the string on the instrument to the tailpiece. The tailpiece is usually provides for an opening or recess sufficient in size to receive the strings of various diameters ranging from 0.007″ to 0.070″ or more while being smaller than the diameter of the ball end so as to limit the passing of the ball end through the opening or recess in order to secure or mount the individual strings to the body. The wrapping usually extends up to a ½″ towards the plain end and as such the position of the tailpiece structure relative to the bridge element must insure that the wrapping does not extend over the second critical point when arranged on the instrument; this wrapping, under normal circumstances, is not subject to stretch compared to the rest of the string. Stable fine adjustments of these and other elements have been a longstanding goal for stringed musical instruments.
In the relevant art, “anchoring” strings is often referred to as attaching or securing a string and understood with the limitation that the anchoring is sufficient so that the string is fixedly attached or secured to the instrument under the typical tensioned conditions of the string.
In the Proelsdorfer U.S. Pat. No. 2,304,597, string tensioning devices placed on the tailpiece for fine tuning the pitch of the strings of violins, guitars and the like, were disclosed; such pitch adjustment is quite limited in range, an interval falling between that of a whole tone and a minor third at best, and designed to offer the tuning of the strings a minor adjustment of pitch after the general tuning is achieved with the tuning pegs on the head of the instrument which traditionally first provides for raising and adjusting the tension of the strings to pitch from an untensioned condition. This is regarded as fine tuning and the apparatus for doing so, the “fine tuners”, usually comprise an adjustment knob or thumb screw.
It is known to those skilled in stringed musical instrument design and construction that various tremolos have been proposed and utilized for varying the tension of all the strings simultaneously for the purpose of creating a “vibrato” and what has come to be known as a “tremolo” sound since the 1950's. Further, it is known to those skilled in the art that there are a great many commonly used names for such devices, such as tremolo, tremolo device, tremolo tailpiece, tremolo bridge, fulcrum tremolo, fulcrum tremolo bridge, fulcrum tremolo tailpiece, fulcrum tremolo bridge-tailpiece, vibrato, vibrato bridge, vibrato tailpiece, vibrato bridge tailpiece, etc.
In one specific species, known as the fulcrum tremolo, first introduced in Fender U.S. Pat. No. 2,741,146, shows and provides a device comprising a novel structure which incorporates the bridge and the tailpiece. The portion supporting the bridge elements is called the bridge plate or the base plate. Further, the bridge and the tailpiece connected to the base plate both move together as the fulcrum tremolo device is pivoted around a common axis transverse the direction of the strings. Accordingly, a singular and defining aspect of the fulcrum tremolo is that the harmonic tuning is upset as the device is pivoted; and, accordingly, for an instrument equipped with a fulcrum tremolo, restoring any or all of the strings to a proper pitched condition also simultaneously restores the harmonic tuning where otherwise all other conditions remain essentially the same. The base plate upon which the individual bridge elements are adjustably secured has a beveled ridge portion closest the nut which is secured to the instrument body by six screws along a common axis, or fulcrum pivot axis, permitting pivotal movement of the device which varies the tension on the strings and produces the desired tremolo effect.
In this first vintage system, herein referred to as Type I, the metal bridge elements of '146 which are stamped and folded into the suitable form are loosely held in place by a spring loaded attachment screw arrangement pivotally secured through openings in a small bent portion of the base plate farthest from the fulcrum axis. The bridge elements also incorporate setscrews for varying the relative height of the bridge elements and, therefore, height of the respective second critical points to the base plate and by extension, the body and neck. Later iterations of Fender '146 included pivotally supporting the fulcrum tremolo relative to the body by a riser posts arrangement adjustably connected to the fulcrum tremolo. Riser posts have existed since at least the 1950's and typically include an annular flange for supporting a device. The horizontal distance between the vertical centerline of each riser post is approximately 2.22″. Further, the distance from the pivot point to the second critical point not including the variable heights of the bridge elements is 0.25″ and the distance from the nut to the pivot is about 25.25″ since the Fender Stratocaster for which this fulcrum tremolo first appeared provided a 25.5″ scale length.
Typically, in order to facilitate the fulcrum tremolo pivoting about its fulcrum axis, counter springs are utilized to counteract or counter balance the pull of the strings. Counter springs are usually connected to the body of the instrument at one end and, on the other end, to a separate spring attachment means usually a block of metal, milled or cast or a combination of the two, and being secured to the bottom of the base plate by three screws 90 degrees to the base plate is often called a spring block.
One of the most profound goals with prior art has been maintaining the initial tuning at proper playing pitch. When a musician plays on the string there is usually some kind of string stretch over time that results in the overall tuning going out of balance. Specifically, when the pitch of the string changes, the position of the fulcrum tremolo and the position of the second critical point relative to the nut changes which then alters the harmonic tuning.
Initial position refers to the specific equilibrium point between the tension of the strings and the tension of the counter springs at the intended tuned pitched condition of the strings when harmonic tuning is achieved. Often the pivot means is subject to wear and the tremolo does not always return to its initial position. Great care is required to establish the initial position since both aspects of adjustment are interactive and it simultaneously provides both the proper harmonic tuning and proper pitch tuning for each of the individual strings.